What regression testing is

Regression testing ensures:

• new changes don’t break existing features

It’s triggered by:

• bug fixes
• refactors
• new features
• dependency upgrades

Manual vs automated regression

• manual regression: slow but useful sometimes
• automated regression: fast and repeatable

Build a regression suite

Start with:

• critical user flows
• high-risk modules
• recently buggy areas

Diagram: change → regression safety

  graph LR
A[New change] --> B[Run regression]
B --> C{All pass?}
C -- Yes --> D[Ship]
C -- No --> E[Fix + add test]
E --> B